title: High-yielding, regiospecific synthesis of cis(4,4')-di(carbomethoxybenzo)-30-crown-10, its conversion to a pyridyl cryptand and strong complexation of 2,2'- and 4,4'-bipyridinium derivatives.
abstract: A high yielding (93%), regiospecific synthesis of cis(4,4')-di(carbomethoxybenzo)-30-crown-10 (1c) is reported. The derived crown ether diol 1d was converted to pyridyl cryptand 12 in 44% yield by reaction with pyridine-2,6-dicarbonyl chloride. Binding of two different 4,4'-bipyridinium (paraquat) species (3) and 2,2'-bipyridinium (diquat) 4 by 12 was explored via (1)H NMR spectroscopy, NOE experiments, mass spectrometry, X-ray crystallographic analyses, and isothermal titration calorimetry. Cryptand 12 exhibits the highest association constant for diquat ever reported (Ka = 1.9 x 10(6) M(-1)) and very high association constants for paraquats (Ka > 10(5) M(-1)) in acetone at 22 degrees C. The binding constant of diquat 4 by cryptand 12 is nearly 6-times higher than any other reported host.
authors.affiliation: Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0212, USA.
authors.forename: Adam M-P
authors.initials: AM
authors.lastname: Pederson
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Ward
authors.forename: Daniel V
authors.initials: DV
authors.lastname: Schoonover
authors.forename: Carla
authors.initials: C
authors.lastname: Slebodnick
authors.forename: Harry W
authors.initials: HW
authors.lastname: Gibson